And now for our regular primer on global economics, no student loan required. Remember the European economic crisis? Just months ago, there was near panic that the euro zone would collapse, bringing down with it the entire international economy, again. So, how is Europe doing now and what is the overall state of the global economy? Well, one place economists look for answers to those questions is in the exchange rate between dollars and euros.

Adam Davidson of NPR's Planet Money team joins us frequently to help us navigate global economics. Adam, welcome once again.

ADAM DAVIDSON, BYLINE: Hi, Robert. Thanks.

SIEGEL: And the exchange rate between dollars and euros, if I'm not planning a trip to Paris, why would I look at that?

DAVIDSON: I'm a real fan of the exchange rate between dollars and euros as the sort of ignored, unheralded indicator that has enormous value. Every minute of every day, about a billion dollars is traded between the U.S. and Europe in currency. And it tells you this constant ticker of how people with money think the global economy is doing. It's always there, but it's always helpful.

SIEGEL: Now, we're not just talking about tourists exchanging dollars for euros or vice versa to make a trip across the Atlantic. We're talking about speculation.

DAVIDSON: Yeah, the vast, vast majority of dollars and euros that change hands comes from really, really rich people, really huge institutions - banks, central governments - that are trying to figure out how to keep their money safe or where it's going to do best. Something like $1.5 trillion is exchanged a day between the U.S. and Europe. If you add up all the tourists from the U.S. going to Europe, all the tourists from Europe going to the U.S., all the goods we exchange, all of that together is less than a trillion dollars.

So between right now and noon tomorrow, financial speculators will trade more dollars than in the entire year of real business.

SIEGEL: OK, so what conclusions can we, and should we draw, from all the actions of all those currency speculators in Wall Street and in the European financial centers?

DAVIDSON: I think it's really reassuring. If you look at the euro-dollar exchange rate, you see that for much of the crisis - from 2007 right until about September of last year - it's hurtling upwards, hurtling downwards. Every single bit of news, you know, the U.S. banks coming close to collapse, European governments coming close to collapse, Ben Bernanke saying almost anything at all, it's very twitchy. But since September, it's just been - it goes up and down a little. You know, a hundredth of a penny, three hundredths of a penny.

It's a very narrow, confined movement, which tells you that financial investors - who are the twitchiest lot of people in the world - are feeling much more sanguine. Even when there's bad news, even when there's confusing news, they say: You know what, it looks like things are pretty stable.

SIEGEL: So now that the days of volatility are behind us, who won when the rate of exchange was fluctuating, you know, 5, 10 percent, say?

DAVIDSON: That was my big question. You know, is it a really good time for people with dollars to go to Europe and have a discount vacation? Or is it - like, I remember 20 years ago, there was a moment when it was really cheap for Germans to come to the U.S., and it seemed like America was overrun with German tourists because the deutsche mark was really strong at that moment. Well, we are exactly where we were just before the financial crisis.

One euro buys about a buck and a quarter. That's pretty much exactly where we were right before the financial crisis. So all the hurtling up, hurtling down, we end up exactly where we were when we started.

SIEGEL: I guess I have the question that I have about other markets, say, the stock market, which is how related to the real world is all of this. That is, Greece still seems to be in trouble. Portugal still seems to be in trouble. The countries that had us worrying about the euro don't seem to have solved their problems all that thoroughly. Should we stop worrying about the euro zone collapsing?

DAVIDSON: We absolutely should not stop worrying. But what we do learn is that when the world's richest people and companies and governments actually put their money on the table, what they seem to feel at this moment is that these factors are not as alarming as they were a year or two ago. We might be going back to where we have always been, which is it's a scary, uncertain world we live in. It's just normally scary and uncertain, not insanely out of control scary and uncertain.